1) Symbols decoded into clever rhyming phrases.
No. We haven't even decoded prince's symbol beyond some vague androgyny. Not only that, but you can't list an episode title as a symbol in TV guide. Rhyming phrases will stick around because they work.
2) Altered expanded opening title.
Possible. The opening title will have to stay short, due to the packed nature of the show, but as for putting little bits into, that's entirely plausible, though not necessary, and it simpy may never happen.
3) Hiro's Sword as his Kryptonite
Clearly no, it's a betrayal to the storyline, getting the audience all hooked up to have Hiro back in full stride and then snatching it away again, Lost-Style. An obviously bad move. And we've seen future Hiro use his power AND the sword. Moving on...
4) Claire's School
Is history... we'll never see it again, much less rivals from the cheer squad "on her heels." HAHAHAHAHAHA. Next.
5) Nikki's third persona
Well, while it's obvoiusly not multiple personality disorder, as much as people seem to like to call it that, given that Nikki' is acquiring these minds, or Jessica is brain hopping, a third personality doesn't seem so odd. A third person in Nikki's mind is a complete possibility.
6) Simone with powers
Officially debunked... though we will see her again, not only as an illusion/dream/hallucination in #18, but also during any further dreams or time jumps that involve her specifically... count on it.
7) Heroes' title choice and E shore media.
Obviously heroes was chosen because it was origionally conceived of as a superhero show. Will alternate websites with clever anagrams come about? Certainly. We already have OWI, the most hypocritical title I've ever heard...
8) Peter as the source of all powers
Dr. Suresh told us that Peter was the most important, but Why? There's something here, it isn't Peter as the source, or else Claude and the Haitian, among others, couldn't get powers, but Peter is something, perhaps he has a master gene or some such... it could be any number of things, besides the fact that he is, potentially, the most powerful.
9) Font change
Now I know it was a brainstorm meeting, that's obviously a joke out of context.
10) Micah Sanders Spinoff
What good idea has ever involved the words "Part Silver Spoons?" I love Micah, and the actor is great, and they should show more of him, he'd be a great sidekick for just about anybody on the show, but no, a spinoff with a character that's had, at most 40 minutes of screen time all season isn't even half-serious.
11) Isaac cuts his hair
Well, assuming he doesn't get his head chopped off, why not?
12) The Nuke WILL go off.
I actually buy this one. All of Isaac's other paintings have come completely true. There's nothing to say the nuke CAN'T go off... I wouldn't count out Ted, just because everyone's so excited about it being Peter... the concept of him overloading and exploding nuclear style was never actually explained and makes no sense within the parameters of the show.
13) Second season starts 20 years ago.
Starts? I can certainly believe that, we've already had two flashback episodes, not counting the one Hiro spent in the future. Having two, even three episodes set 20 years ago seems entirely plausible, especially if we're setting up a whole season worth of stories. Will they actually do it? Not likely, one episode seems like enough... but honestly, this one's entirely possible...